IB ESS HL 2.1.23 Keystone Species Question Bank
Explain how keystone species can have disproportionate effects on community structure and function.
- Syllabus
- First assessment 2026
- Course
- ESS HL
- Level
- HL
Exam points
- identify the population or ecosystem process in the evidence
- apply the correct interaction, growth or sampling model
- justify the conclusion using limiting factors, assumptions and uncertainty
2.1.23—Keystone species question 1
Figure A simplified food web in a kelp forest ecosystem
Figure Kelp forest ecosystems with and without the presence of sea otters
The arrows indicate the flow of carbon between the atmosphere and the carbon stored in kelp.
Question (a)
(a)
Outline why sea otters are considered a keystone species.
[ 1 ]
Question (b)
(b)
Explain how sea otters contribute to the resilience of the kelp forest ecosystem.
[ 3 ]
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